The object of the proposed research is to continue studies on the reactions of singlet oxygen with organic substrates, particularly those systems which are key components in biological systems. Particular attention will be given to oxazoles, imidazoles, enamines and enols. In addition, studies on benzofurans related to the psoralens will be continued in order to determine correlations between reactivity with singlet oxygen and biological activity. The research will involve model studies on the mechanism by which singlet oxygen may be transferred to acceptors in biochemical processes. Donor molecules to be studied will include 9,10-diphenylanthracene peroxide fused to a crown-ether binding site, capable of releasing molecular oxygen on thermolysis. Acceptors will incorporate a residue capable of complexing with the ether portion of the donor, and separated from the acceptor site by a carbon chain of suitable size. The acceptor substrates will consist of suitable unsaturated systems.